FIGS. 1 to 3 show a prior art apparatus of this kind. In the figures, the reference numeral (1) designates water to be tested, (2) a water quality detector, (3) a base, (4) a moving wheel, (5) and (6) designate supporters, (7) designates a container for containing a winding device, (8) a handle for raising and lowering operation, (9) a fitting plate, (10) a worm shaft, (11) a worm secured to the worm shaft (10), (12) a winding shaft, (13) a worm wheel and (14) a winding drum which is fixed together with the worm wheel to the winding shaft. The reference numeral (15) designates a wire having one end secured to the drum to control the raising and lowering of the water quality detector (2). The reference numeral (16) designates a pulley, (17) a guide roller, (18) a guide roller shaft, (19) a movable frame, (2) a water quality detector supporting arm, and (21) a bracket for holding the detector (2).
A description will now be made be made of the operation of the apparatus. In raising and lowering, the worm (10) and the worm wheel (11) in the container (7) are rotated by the revolution of the handle (8) with the consequence that the winding drum (14) is rotated through the worm wheel meshed with the worm (11). since this revolution causes the wire (15) to be wound, the movable frame (19) connected to one end of the wire (15) is vertically moved by the aid of the roller shafts (18) and the guide rollers (17) mounted on the movable frame and the supporters (5), (6). Thus, the water quality detector (2) is vertically moved through the bracket (21) and the water quality detector supporting arm (20) fixed to the movable frame (19).
In the conventional lifting apparatus described above, a winding drum for winding the wire has been needed and furthermore, when the apparatus is a substantial height, it has been necessary to use a large drum and movable frame. When the water quality detector is lowered by rewinding the drum (14) to loosen the wire (15) so that the deadweights of the water quality detector (2) and the movable frame (19) pulls them down, a smooth lowering operation can not be attained due to the small load and the frictional resistance of the sliding parts. Additionally, it has been disadvantageous in that it is difficult to conceal the container for containing the winding device and the movable frame guide rollers from the atmosphere and two supporters are needed thereby resulting a large apparatus.